Hard disk drive for perpendicular recording with transducer having submicron gap between pole tips

ABSTRACT

An information storage system includes a transducer having a loop of ferromagnetic material with pole tips separated by an nonferromagnetic gap located adjacent to a medium such as a rigid disk. During writing the separation between the pole tips and the media layer of the disk is a small fraction of the gap separation. Due to the small separation between the pole tips and the media layer, the magnetic field generated by the transducer and felt by the media has a larger perpendicular than longitudinal component, favoring perpendicular recording over longitudinal recording. The media may have an easy axis of magnetization oriented substantially along the perpendicular direction, so that perpendicular data storage is energetically favored. The transducer may also include a magnetoresistive sensor for reading magnetic information from the disk.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation and claims the benefit under 35U.S.C. Section 120 of pending U.S. patent application Ser. No.10/006,453, filed Nov. 19, 2001, which claims priority to U.S. Pat. No.6,320,725, filed Dec. 22, 1995, U.S. Pat. No. 6,493,191, filed Sep. 15,1995, U.S. Pat. No. 6,600,631, filed Nov. 14, 1994, abandoned U.S.patent application Ser. No. 08/673,281, filed Jun. 28, 1996, U.S. Pat.No. 6,212,047, filed Dec. 20, 1996, U.S. Pat. No. 6,198,607, filed Oct.2, 1996, U.S. Pat. No. 6,160,685, filed Aug. 26, 1996, U.S. Pat. No.5,949,612, filed Aug. 15, 1995, and U.S. Pat. No. 5,550,691, filed Oct.22, 1992, all of which are incorporated by reference herein

TECHNICAL FIELD

The present disclosure relates to systems for electromagnetic storageand retrieval of information, such as disk drive system and components.

BACKGROUND

Hard disk drives have traditionally employed electromagnetic transducersthat are spaced from a rapidly spinning rigid disk by a thin layer ofair that moves with the disk surface. Such a spacing is believed to beimportant in avoiding damage between the rapidly spinning disk and thetransducer, which is constructed with an aerodynamic “slider” designedto “fly” slightly above the disk surface, buoyed by the moving airlayer. This spacing or fly height, however, limits the density withwhich data can be stored and lowers the resolution and amplitude withwhich data can be retrieved.

Data is conventionally stored in a thin media layer adjacent to the disksurface in a longitudinal mode, i.e., with the magnetic field of bits ofstored information oriented generally along the direction of a circulardata track, either in the same or opposite direction as that with whichthe disk moves relative to the transducer. In order to record such alongitudinal bit in the media layer, the transducer has a ring-shapedcore of magnetic material with a gap positioned adjacent to the disk,while current in a coil inductively coupled to the core induces amagnetic field adjacent to the gap strong enough to magnetize a localportion of the media, creating the bit. This type of transducer iscommonly termed a “ring head.” The media layer for this form of datastorage has an easy axis of magnetization parallel to the disk surface,so that writing of bits in the longitudinal mode is energeticallyfavored. Since adjacent bits within the plane of the thin film mediahave opposite magnetic directions, demagnetizing fields from adjacentbits limit the minimum length of a magnetic transition between suchbits, thereby limiting the density with which data can be stored andlowering the signal-to-noise ratio at high bit densities. Moreover, athigh bit densities, the transition location between longitudinal bits ismore difficulty to control, increasing errors known as “bit shift”.Also, overlap between adjacent longitudinal bits of opposite polaritycan result in reduced transition amplitude at higher bit densities,termed “partial erasure” and reducing the signal to noise ratio since alarger fraction of each bit is degraded by the transition. At very highdensities, demagnetization of the oppositely directed longitudinal bitsmay occur over time, resulting in data loss.

Perpendicular data storage, in which the magnetic data bits are orientednormally to the plane of the thin film of media, has been recognized formany years to have advantages including the relative absence of in-planedemagnetizing fields which are present in longitudinal data storage. Inaddition to potentially achieving sharper magnetic transitions due tothe reduction of bit shift and partial erasure, perpendicular datastorage may offer a more stable high density storage, at least formultilayered media. Despite these advantages, perpendicular data storagehas not yet seen commercial success. The system typically proposed forperpendicular recording includes a transducer having a single pole,commonly termed a “probe head.” In order to form a magnetic circuit withthe probe head, a magnetically soft underlayer adjoins the media layeropposite to the pole, the underlayer providing a path for magnetic fluxthat flows to or from the transducer through a return plane of the headseparate from the pole.

Several disadvantages of the probe head and underlayer system have beendiscovered. Comparison of a probe head with a ring head having a gap ofa thickness equal to that of the single pole has revealed that thelongitudinal fields from the ring head are more spatially localized thanthe perpendicular fields from the probe head, since the field lines in aring head span from the closest edges of one pole to the other acrossthe gap, while the field lines in the single pole probe head radiatefrom both the probe tip and the sides of the probe toward the underlayer(unless the pole tip contacts the underlayer), the field lines from thesides of the probe essentially broadening the transition beyond thedimensions of the probe tip. Moreover, the ring head has a singleamagnetic gap, while the probe head has two gaps: one between the probeand underlayer and one between the return plane and the underlayer. Thepresence of this second gap renders the probe head extremely sensitiveto external stray fields. Due to the high reluctance of the second gap,stray fields entering the head are channeled directly through the probeand across the media. Calculations show that a 5 Gauss (G) stray fieldcan easily be amplified to 2000 G at the center of the media, largeenough to cause erasure, which we have observed in the laboratory.

One of the advantages of the probe head and underlayer recording systemis that the write fields produced between the probe and underlayer aregenerally stronger than those attained underneath the gap of a ringhead. There is a disadvantage to the high write fields, however, inheads of insufficient stability, since domains oriented parallel to theprobe can induce fields at the media gap which are strong enough toerase data, another effect which we have observed empirically. Moreover,achieving an efficient magnetic circuit in the probe head and underlayersystem is difficult. During head fabrication, great care is taken tomagnetically align the easy axis of the permalloy yoke perpendicular tothe direction of magnetic flux flow. While this may be relativelystraightforward to accomplish in the small magnetic structures of thehead, it is problematic for large circular structures such as the softmagnetic underlayer of the disk, which forms part of the magnetic fluxcircuit in the probe head system. As a result, the permeability of theunderlayer has generally been unsatisfactory and inhomogeneous, and themagnetic circuit therefore inefficient.

The possibility of employing a flying ring head in combination withmedia having a perpendicular anisotropy appears to have been originallyproposed in an article entitled, “Self-Consistent Computer CalculationsFor Perpendicular Recording,” IEEE Transactions On Magnetics, September1980, by Potter and Beardsley. A difficulty in the system described inthis article is that the maximum perpendicular component of the magneticfield transmitted from the head to the medium is substantially less thanthe maximum longitudinal component of that field. Wang and Huang, in“Gap-Null Free Spectral Response of Asymmetric Ring Heads ForLongitudinal and Perpendicular Recording”, IEEE Transactions OnMagnetics, September 1990, calculate the magnetic fields transmittedfrom a ring head that has a gap angled away from normal to a medialayer. Similarly, Yang and Chang, in an article entitled “Magnetic Fieldof an Asymmetric Ring Head with an Underlayer”, IEEE Transactions OnMagnetics, March 1993, calculate the magnetic fields transmitted from aring head with a slanted gap, and include a soft magnetic underlayeradjacent to the media to complete the magnetic circuit of the ring head.

Osaka et al., in the article “Perpendicular Magnetic Recording ProcessOf Electroless-Plated CoNiReP/NiFeP Double Layered Media With Ring-TypeHeads”, look at recording performance of flexible double layeredmagnetic media to measure the effect of various coercivity underlayers.And Onodera et al., in the article “Magnetic Properties And RecordingCharacteristics of CoPtB—O Perpendicular Recording Media” investigatehow varying the proportion of oxygen can be used to control theperpendicular anisotropy and coercivity of that media, which is measuredwith a metal-in-gap video cassette recorder ring head. More recently,U.S. Pat. No. 5,455,730 to Dovek et al. proposes a disk drive systemwith a slider that skis on a liquid spread atop a wavy disk, with atransducer stepped back from the support surface having amagnetoresistive sensor and an electrical means for compensating for abaseline modulation induced by the temperature sensitive waviness of thedisk. Unfortunately, the spacing added by the liquid and the distancebetween the bottom of the carrier and the transducer reduces datastorage density and resolution.

What is needed is a system that affords the advantages of perpendiculardata storage in a durable, high density, hard disk drive system.

SUMMARY

The present disclosure is directed to an information storage systememploying a microscopic transducer having a loop of ferromagneticmaterial with pole tips separated by an nonferromagnetic gap locatedadjacent to a medium such as a rigid disk. During writing of a magneticsignal to the disk the separation between the pole tips and the medialayer of the disk is maintained at a small fraction of the gapseparation. Due to the small separation between the pole tips and themedia layer, the magnetic field generated by the transducer and felt bythe media has a larger perpendicular than longitudinal component,favoring perpendicular recording over longitudinal recording. Moreover,the head to media separation is small enough to allow a significantreduction in the gap size without causing the longitudinal fieldcomponent to predominate over the perpendicular field component,providing further increases in data density. The media may have an easyaxis of magnetization oriented substantially along the perpendiculardirection, so that perpendicular data storage is energetically favored.The transducer may also include a magnetoresistive sensor for readingmagnetic information from the disk.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a greatly enlarged, simplified, cross-sectional view of aportion of a data storage system in accordance with the presentinvention.

FIG. 2 shows a plot of longitudinal and perpendicular field componentsof the magnetic field transmitted from the pole tips to the medium ofthe data storage system of claim 1.

FIG. 3 shows a plot comparing maximum strength perpendicular andlongitudinal magnetic field components transmitted from the pole tips ofFIG. 1 at various distances from the head.

FIG. 4 is an enlarged perspective view of a generally plank-shapedembodiment of a transducer holding the pole tips of FIG. 1 in one ofthree disk-facing projections.

FIG. 5 is a bottom view of the transducer of FIG. 4.

FIG. 6 is a cross-sectional view of a magnetically active portion of thetransducer of FIG. 4.

FIG. 7 is an opened up bottom view of the magnetically active portion ofFIG. 6.

FIG. 8 is a further enlarged bottom view of the magnetic pole structureof FIG. 7.

FIG. 9 is a fragmentary cross-sectional view of an embodiment having apole structure including a high magnetic saturation material adjoiningthe gap and one of the pole tips.

FIG. 10 is a plot of the field strength of the embodiment of FIG. 9.

FIG. 11 is a fragmentary cross-sectional view of an embodiment having apole structure including a high magnetic saturation material adjoining aslanted gap and one of the pole tips.

FIG. 12 is a cross-section of the embodiment of FIG. 9 and including amagnetoresisitve sense element adjacent to the magnetic core and distalto the pole structure.

FIG. 13 is an opened up top view of the magnetoresistive sense elementand magnetic core of FIG. 12.

FIG. 14 is an enlarged cross-sectional view illustrating the formationof the magnetoresistive sense element and magnetic core of FIG. 13.

FIG. 15 is an enlarged cross-sectional view illustrating the formationof a conductive terminal and lead to connect with the magnetoresistivesense element of FIGS. 11-13.

FIG. 16 is a cross-sectional view shows later steps in the formation ofthe embodiment of FIG. 12.

FIG. 17 is an opened up top view of the coil layer of the embodimentshown in FIGS. 11 and 14.

FIG. 18 is a cross-sectional view illustrating a subsequent stage in theformation of the embodiment of FIG. 12 that focuses on the constructionof the high magnetic saturation layer of FIG. 9.

FIG. 19 is a cross-sectional view illustrating a subsequent step in theformation of the embodiment of FIG. 12 that focuses on the constructionof the gap of FIG. 9.

FIG. 20 is a cross-sectional view illustrating a later step in theformation of the embodiment of FIG. 12 that focuses on the constructionof the pole tips of FIG. 9.

FIG. 21 is a top view of the pole tip construction of FIG. 20.

FIG. 22 is a cross-sectional view of the formation of a durable padencasing the pole tips of FIG. 9.

FIG. 23 is a cutaway bottom view of a flexure beam and gimbal to whichthe transducer of FIG. 12 is attached.

FIG. 24 is an opened up top view of a disk drive system employing thetransducer of FIG. 12 and the beam of FIG. 23.

FIG. 25 is a highly magnified cross-sectional view of a magneticrecording surface having a high perpendicular anisotropy.

DETAILED DESCRIPTION

Referring now to FIG. 1, a greatly enlarged cross-sectional view of aninformation storage system in accordance with the present inventionfocuses on a pair of pole tips 20 and 22 of an electromagnetictransducer 25 that are separated by an amagnetic gap 27, the transducersliding on a rigid magnetic recording disk 30. The disk 30 in thissimplified drawing has a media layer 33 disposed between a substrate 35and a protective overcoat 38, and a surface 40 on which the transducer25 slides, the disk moving relative to the transducer in a directionshown by arrow 41. As a descriptive aid, a direction normal to disksurface 40 is termed the perpendicular or vertical direction, while adirection parallel to the disk surface 40 is defined in terms of lateraland longitudinal directions. The gap 27 has a longitudinal extent Gseparating the pole tips 20 and 22 that is several times a perpendiculardistance D separating the pole tips from the media layer 33, distance Dincluding the thickness λ of the overcoat 38 and any lubricant, notshown, disposed atop the overcoat. The media layer 33 has a thickness δsuch that the perpendicular distance D from a midpoint of the medialayer 33 and the pole tips 20 and 22 is a fraction of the gap extent G.A number of magnetic fields lines 42 produced by the transducer 25during writing of data on the disk 30 travel both directly across thegap 27 and radiate in a semicircular fashion from one pole tip 20 to theother 22 through the media layer 33. The field lines 42 that penetratethe disk 30 are most concentrated adjacent to corners 44 and 46 ofrespective pole tips 20 and 22.

In FIG. 2, the field lines 42 of FIG. 1 are displayed in terms of themagnitude of longitudinal 50 and perpendicular 52 components felt by themedia layer 33 at a perpendicular distance D from the pole tips 20 and22 that is in the neighborhood of one-tenth the gap spacing G. Thedimensions along the horizontal axis of this figure are depicted withthe gap spacing G being equal to unity. The longitudinal component 50can be seen to have the shape of a symmetrical curve that peaks in themedia layer 33 directly across from a center of the gap 27. Theperpendicular component 52, on the other hand, has zero strengthdirectly opposite from the center of the gap 27, and a peak in magnitudedirectly opposite both of the corners 44 and 46, the peak oppositecorner 46 having a negative value to reflect that the perpendicularcomponent opposite corner 46 is oppositely directed relative to theperpendicular component opposite corner 44. Note that the perpendicularcomponent 52 of the magnetic field felt by the media has a magnitudenearest the corners 40 and 44 that exceeds the maximum magnitude of thelongitudinal component 50, encouraging perpendicular data storage in themedia layer.

FIG. 3 compares a maximum longitudinal field component 55 with a maximumperpendicularly oriented field component 57 over various perpendiculardistances D from the pole tips 20 and 22. As can be seen in the previousfigure, the maximum longitudinal component is found directly oppositethe center of the gap whereas the maximum perpendicular component occursdirectly opposite corners 44 and 46. In FIG. 3 the longitudinal fieldstrength deep within the gap 27 has been given a unitary value forreference, and the vertical distance D from the pole tips 20 and 22 isgiven in units for which a distance D equal to the gap width G is equalto one. It is apparent that the maximum perpendicularly oriented fields57 vary with distance D from the pole tips 20 and 22 much moredramatically than the maximum longitudinally oriented fields 55 fordistances D less than about one-quarter of the gap spacing Q such thatthe perpendicular fields are stronger than the longitudinal fields atvertical distances from the pole tips that are a small fraction of thegap width G, while the longitudinal fields are stronger than theperpendicular fields at distances D further than a fraction of the gapwidth.

A gap-to-media spacing ratio of ten, which is in a range for which theperpendicular field component would dominate, is approximately presentin a sliding contact hard disk drive embodiment having a gap G of 250nm, an overcoat thickness λ of about 150 Å, including surface roughnessand lubricant, and an active media layer 33 with a thickness δ of 200Å., or a half thickness of about 100 Å. By comparison, a conventionalflying transducer having a similar gap spacing employed with a diskhaving a similar overcoat may have an additional spacing due to theflying height that adds perhaps 40 nm to 100 nm between the pole tipsand the media layer, pushing the gap-to-media spacing ratio to a levelat which the maximum longitudinal field component felt by the media islarger than the corresponding perpendicular field component. For a diskwith a media 33 composed of a number of thin multilayers and a roughly10 nm overcoat 38 (including lubricant), the gap 27 may have a width Gas small as 0.15 μm and still enjoy a gap-to-media spacing ratio of ten.Such a small gap spacing provides sharper field gradients which affordhigher density recording and reading, and a gap as small as 0.10 μm andsmaller may be employed to record and read perpendicularly stored data.The employment of media having a high perpendicular anisotropy and lownoise is also beneficial, particularly for the situation in which theperpendicular write fields from the head do not clearly dominate.

As will be discussed below, data retrieval may be inductivelyaccomplished or, preferably, a magneto-resistive (MR) reading elementmay be incorporated adjacent to the magnetic core. In the situation forwhich the MR element is separated from the core, the MR element sensesperpendicular fields and thus receives a greater signal fromperpendicularly magnetized media, rather than the perpendicularoffshoots of longitudinally magnetized media, providing a clearadvantage to perpendicular data storage. For a transducer which readseither inductively or with an MR element piggybacked to a magnetic core,the sensitivity of the head during reading will be proportional to theefficiency of that head during writing, via the rule of reciprocity.Moreover, the sensitivity of the head in reading signals involves headsensitivity fields that have a direction which mirrors that of the writefields of the head. Thus, just as the perpendicular component of thewrite fields tends to dominate the longitudinal component at head tomedia spacings that are a small fraction of the gap width, reading ofthe perpendicularly magnetized bits of the media is favored at suchsmall head to media spacings, as the head sensitivity fields have alarger perpendicular than longitudinal component in this situation. Anadvantage of the extremely close head to media spacing afforded by thesliding contact can be seen by looking at the steep slope of theperpendicular field component 57 for distances less than, for instance,one-fourth of the gap width, and realizing that the increase in fieldstrength afforded by such close spacing applies for reading sensitivityas well as writing strength, thus compounding the overall increase inperformance of the head for reading after writing.

Referring now to FIGS. 4 and 5, a greatly enlarged view of a transducer60 which provides durably intimate head-media proximity, therebyenabling perpendicular data storage, is formed as a generallytrapezoidal chip 62 with a surface 65 designed to face a recordingsurface of a rigid magnetic storage disk. The transducer has amagnetically active pad (MAP) 68 that projects from the disk-facingsurface 65 at a location adjacent to a first end 70 of the chip 62 andapproximately equidistant between a right side 73 and a left side 75 ofthe chip. A pair of magnetically inactive pads (MIPS) 78 and 80 projectfrom the disk-facing surface 65 adjacent to a second end 72 of the chip62, MIP 78 being disposed about the same distance from side 73 as MIP 80is from side 75. The three pads 68, 78 and 80 are spaced apart from eachother to provide a stable support structure for the transducer 60, likea table with three short legs that can maintain contact with anyconventional disk surface. An exposed pair of magnetic pole tips 20 and22 are located on a bottom surface of MAP 68, with an amagnetic gap 27disposed between the pole tips 20 and 22. The term “amagnetic” is usedin the current disclosure to describe materials that are notferromagnetic, including paramagnetic and diamagnetic materials.Preferably the gap is formed from a diamagnetic material so that amagnetic field across the gap is obstructed, encouraging a magnetic fluxpath that travels around the gap, increasing the perpendicular componentof the field adjacent to the gap. The pole tips 20 and 22 are ends of aloop-shaped core of magnetic material that is embedded in the chip 62and not shown in this figure.

The loop-shaped core extends within a transduction section 88 further inthe longitudinal direction than in the vertical or lateral direction,and is inductively coupled within that area 88 to a coil which windsrepeatedly around the core, as will be seen in greater detail below. Theprotrusion of the pole tips 20 and 22 from the disk-facing surface 65allows the core to contact the disk, reducing the spacing between thecore and the media layer of the disk while lifting the disk-facingsurface of the chip 62 from the influence of the thin film of air movingwith the disk. As will be seen, the entire chip 62 is constructed of acomposite of thin films, and any bulk substrate which was used as a worksurface for forming many thousands of such chips is removed afterformation of the chips. This thin film composite chip 62 is much lighterthan conventional hard disk drive sliders which include bulk substrate,the lighter weight decreasing the inertia of the chip and the power ofimpacts between the chip and a hard disk, thus reducing the probabilityof damage. Such a thin film composite transducer having pole tipsseparated by a submicron gap and contacting a hard disk is alsodisclosed in parent U.S. Pat. No. 5,041,932, along with perpendicularrecording.

The chip 62 may have a thickness measured in the vertical directionbetween the disk-facing surface 65 and an opposed major surface, notshown in this figure, of between about 1 mil and about 5 mils, althoughother thicknesses may be possible, depending upon tradeoffs such asmagnetic constraints and mass. The lateral width of this embodiment ofthe chip 62 is about 20 mils, although this width can vary by more thana factor of two and is set primarily by the separation of the MIPS 78and 80 required for stability. The width can be much smaller about theMAP 68, as discussed below, while still encompassing the transductionsection 88. The MAP 68 and MIPS 78 and 80 extend from the surface 65 anapproximately equidistant amount, which may range between about 2 μm and8 μm, which is sufficient to avoid aerodynamic lifting and to allow forgradual wear without engendering fracturing of those pads or instabilityof the transducer 60. The aerodynamic lifting force is believed to beprimarily due to the disk-facing area of the chip which is in closeproximity with the disk, including the contact area of the pads, and anybowing or tilting of the chip. As will be explained in greater detailbelow, the chip 62 may be intentionally bowed, tilted and/or etched tocreate a negative pressure region between the chip 62 and the spinningdisk, so that the lifting force from the disk-facing area of the chip ismore than overcome by downward force of the negative pressure. An area89 of each of the MIPS 78 and 80 may be as small as 25 μm² or as largeas about 1000 μm², although other sizes are possible based upontradeoffs including, for example, friction, pad wear and manufacturingtolerances. An aspect ratio of the vertical height to the lateral orlongitudinal width of those pads should not be much over 2/1 to avoidfracturing and transducer inefficiency. The length of the chip 72 ofthis embodiment as measured between the first end 70 and the second end82 is about 40 mils, although this can be varied by a factor of two.This aspect ratio is determined primarily by mechanical considerationsregarding the separation of the MIPS 78 and 80 and the MAP 68, aslimited by the space needed for the transduction section 88.

In FIG. 6, a cross-section of the chip that focuses on the transductionsection 88 is shown along a cross-section bisecting the MAP 68, the poletips 20 and 22 and the gap 27. A lower layer 90 which preferably is madeof alumina, but which alternatively may be made of another electricallyinsulative, amagnetic material such as doped silicon, silicon dioxide ordiamond-like carbon (DLC) forms the disk-facing surface 65, while ahard, wearable casing 92 which is preferably made of DLC or another hardamagnetic material such as silicon carbide or boron nitride forms theportion of the MAP 68 surrounding the pole tips 20 and 22. The gap 27 ispreferably formed of an insulative, amagnetic material such as siliconor silicon dioxide which is softer than the hard wear material of thecasing 92. Hydrogenated carbon may also be a desirable gap 27 material,having a hardness that can be adjusted to correspond with the particularpole tips 20 and 22, casing 92 and disk surface characteristics. Thewear material of the casing 92 is preferably made of an amorphousmaterial such as DLC which has a hardness similar to that of a surfacelayer of the disk with which the transducer 60 is to be employed, formatching wear between the transducer and the disk. The casing may bethicker closer to the disk-facing surface 65 for manufacturing anddurability. Adjoining the pole tips 20 and 22 is a bottom yoke 95 ofmagnetic material which extends symmetrically from a pair of slantedsections 98 to a pair of generally planar sections 100. The pole tips 20and 22 and yoke sections 98 and 100 are formed from permalloy or otherknown magnetic materials, while at least one of the pole tips mayinclude a high magnetic moment material, such as cobalt niobiumzirconium (CoZrNb), iron nitride (FeN) or iron nitride alloys such asFeNAl adjacent to the gap 27. The yoke sections 98 and 100 arepreferably formed in a laminated fashion, to be described below, inorder to reduce eddy currents that impede transducer efficiency at highfrequencies. Adjoining the yoke sections 100 are a pair of magneticstuds 101 and 102 that extend to a generally planar magnetic top yoke104 interconnecting the studs 101 and 102. The poles 20 and 22, bottomyoke 95, studs 101 and 102 and top yoke 104 form a generally loop-shapedmagnetic core 106, creating a contiguous magnetic circuit except for thesmall amagnetic gap 27. In a preferred embodiment discussed below, thestuds are eliminated, and the core is formed in a shape having across-section that resembles a clamshell.

A series of electrically conductive coil sections 110 made of copper orother conductive metals or alloys is shown in cross-section in FIG. 3 tobe spaced both within and without the magnetic core 106. Interspacedbetween the coil sections 110 and the core 106 is an electricallyinsulative spacer material 112 such as Al₂O₃, SiO₂ or a hardbakedphotoresist or other polymer. The coil sections 110 can be seen to bedivided into three generally horizontal layers in this embodiment,although more or less layers are possible, depending upon manufacturingand magnetic tradeoffs. These layers of coil sections 110 can also beseen to fall into four horizontally separate groups. Proceeding fromleft to right, these groups are labeled 114, 116, 118, and 120, with acrossover section 122 connecting groups 116 and 118. Although difficultto see in the cross-sectional view of FIG. 6, the coil sections 110 arein actuality a single coil 124 which winds repeatedly about first oneand then the other of the two studs 101 and 102. The groups 114 and 120which are disposed outside the core 106 have an electric current duringwriting or reading which is directed into or out of the plane of thepaper opposite to that of groups 116 and 118 and crossover section 122.The reader may wish to jump ahead temporarily to FIG. 17, which shows atop view of one layer of the spiraling coil 240 much like coil 124,including crossover section 339, corresponding to crossover 122.

Thus a current traveling into the plane of the paper at coil section 126would spiral in the layer of that section 126 around stud 101 with agenerally increasing distance from the stud 101 until reaching coilsection 128, which is connected to section 130 of the next layer. Thecurrent would then spiral inwardly about stud 101 in the layer ofsection 130 until reaching section 132, which is connected to section134 of the next layer. The current would then spiral outwardly aroundstud 101 in the layer that includes section 134 until reaching crossoversection 122, at which point the current would begin to spiral inwardlyabout stud 102, traveling to the second layer at section 135. Thelayered spiraling of the current around stud 102 would continue in asimilar but converse fashion to that described above for the spiralingabout stud 101, until the current exited the coil structure by travelingout of the plane of the paper at section 136. The coil 124 thusresembles interconnected stacks of pancake-shaped spirals centered aboutstuds 101 and 102.

Representative dimensions for this embodiment include an approximately 3μm thick bottom yoke 95 and a top yoke 104 that is about 4 μm inthickness, and studs 101 and 102 which each extend vertically about 23μm between the yokes. The thickness of the bottom yoke 95 is selected tosaturate at a somewhat lower magnetic flux than the pole tips, thuslimiting the flux through the pole tips and avoiding broadening of thetransition that would occur during pole tip saturation. In order toachieve this flux limiting effect with pole tips of different sizes andmaterials, a function can be employed to determine the optimum bottomyoke parameters. The individual coil sections 110 are about 3.5 μm thickmeasured in the vertical direction, and have a center to center spacingof about 5.51 μm in that direction. Longitudinally, those sections 110may be about 2 μm to 4 μm thick within the core 106 with a center tocenter spacing of about 4 μm. The top yoke 104 extends about 169 μmlongitudinally, and the bottom yoke 95 extends similarly but is, ofcourse, split up by the pole tips 20 and 22 and gap 27.

In FIG. 7, a top view diagram of the magnetic core 106 shows that thebottom yoke 95 is shaped like a bow-tie, as the slanted sections 98 aremuch narrower in lateral dimension than the planar sections 100.Diagonal tapered portions 140 of the planar sections 100 funnel magneticflux into the narrower section 98 during a write operation and offer alow reluctance path for such flux during a read operation. Centered atopthe slanted sections 98 are the pole tips 20 and 22, which are separatedby the amagnetic gap 27. The planar sections 100 have a width of about42 μm, which tapers at about a 45 degree angle to a width of about 7 μmat the slanted sections 98. The studs 101 and 102 meet the planarsections 100 distal to the pole tips 20 and 22.

An even more enlarged view in FIG. 8 shows that the pole tips 20 and 22are shaped like baseball homeplates that nearly meet along parallelsides, separated by the long, narrow gap 27. The pole tips 20 and 22 andgap 27 are exactingly tailored to precise dimensions that are chosenbased on a number of parameters. The specific embodiment depicted inFIG. 8 has pole tips that each measure 3.25 μm in the lateral dimensionand 4 μm in the longitudinal direction, before tapering to extendanother 2 μm longitudinally. The peak-to-peak longitudinal dimension ofthe pole tips 20 and 22 and gap 27 is 12 μm. The gap 27 of thisembodiment has a precisely defined longitudinal dimension of 0.26 μm anda lateral dimension of 3.251 μm. As mentioned above, the longitudinalgap 27 dimension may be as small as 0.10 μm or less for extremely highdensity perpendicular data storage applications.

Referring again to FIGS. 1 and 2, it is apparent that the perpendicularfield component 52 felt by the media 33 has an opposite directionadjacent to pole tip 20 compared to that adjacent to pole tip 22. Aslong as the perpendicular field component 52 magnitude is sufficient toeasily magnetize the media 33, the opposite direction of the field doesnot present a problem, since the field adjacent to the trailing pole tip22 will write over the magnetization of the media induced by the leadingpole tip 20. It is advantageous for high coercivity media, however, totransmit a stronger perpendicular field adjacent to the trailing poletip 22 than that adjacent to the leading pole tip 20. Although this maybe accomplished, for example, by creating an asymmetric pair of poletips such that the gap therebetween is angled rather than perpendicularto the media layer 33, a preferable means for achieving a stronger writefield is to sandwich a layer of high magnetic saturation materialbetween the gap and the remainder of the trailing pole tip.

A cross-section of such a pair of pole tips 155 and 157 separated by anamagnetic gap 160 and a high B_(s) layer 162 is shown in FIG. 9. HighB_(s), layer 162 is formed of Fe(Al)N or other known high B_(s)material, and magnetically acts as a part of trailing pole tip 157 thatdoes not saturate at flux levels significantly higher than those whichinduce saturation of leading pole tip 155. Gap 160 is formed of siliconor other amagnetic material having suitable wear characteristics.Surrounding pole tips 155 and 157, gap 160 and high B_(s) layer 162 is ahard, durable material 166 such as amorphous diamond-like carbon, whichis constructed for lasting operational contact with a spinning rigiddisk. Also shown in this figure are bottom yoke sections 170 and 172 ofthe magnetic core, an amagnetic pedestal 175 upon which the yokesections are formed, and an amagnetic isolation layer 177 that forms adisk-facing surface 180. During writing, a magnetic field is induced inthe core preferably at a strength which saturates the leading pole tip155 without saturating the high B_(s) 162 layer of the trailing poletip, so that the field felt by the media is more spread out adjacent tothe leading pole 155 than the concentrated field adjacent to the highB_(s) layer 162 of trailing pole tip 157. The shape of a magneticpattern written on the disk depends substantially upon the shape of highB_(s) layer 162, which is formed as a thin film having a longitudinalthickness of between 100 nm and 400 nm, a lateral thicknessapproximately equal to the track width of 3.25 μm, and a vertical depthof 3 μm to 8 μm. Alternatively, a high B_(s) layer may be formed on bothedges of the gap to enhance writing gradients for the situation in whichthe resulting trailing write fields are sufficient to easily overcomethe magnetization of the media caused by the leading edge.

FIG. 10 shows a perpendicular component 150 of a write field transmittedfrom a head having a high B_(s) layer adjoining a trailing pole tip andfelt by a media layer located at about one-tenth the gap distance fromthe head. As in FIG. 2 the longitudinal distance is given in units ofgap width G, so that zero represents the trailing edge of the gapadjoining the high B_(s) layer, and one represents the edge of the gapadjoining the leading pole tip. As can be seen, the field adjacent tothe trailing pole tip reaches a much higher value than that adjacent tothe leading pole tip, so that the media is magnetized with the trailingsignal without remnant magnetization left from the oppositely directedleading field.

FIG. 11 shows another embodiment of the MAP that provides an assymetricwrite field for perpendicular recording. To construct this embodimentatop the bottom yokes sections 170 and 172, pedestal 175 and insulationlayer 177 that were shown in FIG. 9, a photoresist is patterned atop asputtered conductive seed layer of NiFe so that the resist has an angledoverhang that causes the formation of a slanted edge 182 during platingof a first pole layer which will be subsequently etched to form firstpole tip 184. An amagnetic gap 186 of silicon is then sputtered on theslanted edge 182, on top of which a coating of high B_(s) material 188is deposited. A second pole tip 190 is then formed by firstelectroplating, then lapping to create a surface 192 coplanar with firstpole section 184, and then angled IBE as described above to definevertical, skirted edges of pole tips 184 and 190. Durable wear material195 such as amorphous, diamond-like carbon then encases the pole tips184 and 190, which is then etched and lapped to expose the pole tips 184and 190, completing the formation of assymetric MAP 197. The slantededge 182 facilitates uniform sputtering of the gap 186 and high B_(s),coating 188, as compared to the angled sputtering described above forthe vertically oriented gap 160 and high B_(s) coating 162 depicted inFIG. 9. The angled photoresist overhang which affords formation of theslanted edge 182 can be formed by a number of methods, including the useof either positive or negative photoresists and either angled coherentor incoherent light.

Further improvement to the sliding ring head and perpendicular mediuminformation storage system can be achieved by modifying the transducerof the above described contact planar ring head to include amagneto-resistive (MR) sensor, such a modified transducer 220 beingshown in cross-section in FIG. 12, the orientation of the cross-sectionbeing similar to that of the inductive-only transducer 88 shown in FIG.6. In the embodiment of FIG. 12, an MR element 222 piggybacks the loopshaped core of magnetic material 225 on a side opposite to the pole tips155 and 157. A gap 233 separates a top yoke of the core 225 into firstand second top yoke sections 235 and 237, providing an increase inmagnetic flux passing through MR element 222 during reading of data.Since the pole tips 155 and 157 are closest to the disk duringoperation, the yoke sections 235 and 237 are termed top yokes, while thepair of yoke sections adjacent to the pole tips are termed bottom yokesections 170 and 172. Only a single layer of coils 240 is employed inthis embodiment, which is sufficient for creating a large flux in thecore 220 during writing, additional coil layers of the previousinductively-sensing transducer 88 embodiment not being needed due to theMR sensing element. The bottom yoke sections 170 and 172 connect the topyoke sections 235 and 237 and the pole tips 155 and 157 via a series ofshallow, slanted steps, providing a low reluctance magnetic path whichis especially helpful for high frequency operations. The amagnetic gap160 and high B_(s) layer 162 provide a sharp magnetic transitionadjacent to the border between that gap and high B_(s) layer.

Coupling the MR sensor 222 to the magnetic core 225 far from the poletips 155 and 157 has a number of advantages over conventional MRelements. First, the resistance of MR sensors is known to depend greatlyupon temperature, which may produce spurious readings of the sensor dueto temperature rather than magnetic fluctuations. This temperaturesensitivity is particularly problematic for transducers which contactthe media, as the friction and thermal conductivity created by contactwith the media can result in a thermally induced bias signal that canconceal the magnetic signal desired to be read. The placement of the MRsensor of the current embodiment far from the disk-contacting pole tips155 and 157 and well within the interior of the thin-film slider thatcontains the transducer insulates the sensor from thermal fluctuations,which can improve the magnetic signal to thermal noise ratio by severalorders of magnitude. In addition, piggybacking the sensor 222 to themagnetic core 225 allows the same pole tips that write data to the diskto read that data from the disk, eliminating misregistration problemsthat occur in the prior art due to placement of the MR reading elementapart from an inductive writing element, an advantage that isparticularly helpful at high skew angles. Moreover, since the MR elementis typically very thin and is insulated in this embodiment from the coreby another very thin layer, uniformity and purity of those layers isimportant. Surface irregularities and contaminants typically build upwith each additional layer of the transducer 220, which is constructedin layers generally from the top yoke sections 235 and 237 to the poletip 155. The MR stripe 222 is one of the first layers formed intransducer 220, and benefits from the surface uniformity and lack ofcontamination available at that incipient stage. Finally, removing theelectrically active MR element from exposure to the disk preventsshorting of that element to the disk surface.

FIG. 13 shows a top view of the MR sensor 222 and top yoke sections 235and 237 of the magnetic core 225, as they appear during construction ofthe core prior to the formation of the coil layer. The MR stripe 222 isformed first, atop a planar layer of alumina which has been patterned inareas not shown in this figure to provide electrical interconnection forthe coils and the MR element. The MR stripe 222 in this embodiment ismade of a permalloy (approximately Ni_(0.8) Fe_(0.2)) layer formed to athickness of about 200 Å and having an easy axis of magnetization alongthe directions of double headed arrow 248, the permalloy layer thenbeing covered with a patterned photoresist and ion beam etched to definea generally rectangular shape extending about 5 μm longitudinally andabout 30 μm laterally, although the exact dimensions of the stripe mayvary from these figures by 50%, depending upon tradeoffs involved inmaximizing efficiency and stability. Next, a conductive pattern isformed which provides a pair of conductive leads 250 and 252 to the MRstripe 222, the leads having respective slanted edges 251 and 253 whichare parallel with each other. A bias layer of a permanent magnet or anantiferromagnetic material such as FeMn optionally underlies theconductive pattern adjoining the MR stripe 222, in order to pin themagnetization of that stripe in the direction of arrow 249. An optionalconductive bar 255 or bars shaped as a parallelogram having sidesparallel to edges 251 and 253 is disposed atop MR stripe 222 betweenleads 250 and 253, and additional spaced apart bars may be formed havingsides parallel to edges 251 and 253. The leads 250 and 252 and anyintervening conductive bars 255 are so much more electrically conductivethan the MR stripe 222 that an electrical current between leads 250 and252 in sections 257 of the MR stripe not adjoining leads 250 and 252 orbar 255 flows along the shortest path between the slanted edges 251 and253 and bars as shown by arrows 258, essentially perpendicular to thoseedges and the parallel sides of the intervening bars 255 and at a slantto the easy axis direction 249.

The magnetoresistance of the MR stripe 222 varies depending upon anangle .theta. between the magnetic field and the current in the stripesuch that the resistance is proportional to cos² θ. In the absence of amagnetic field from the yoke sections 235 and 237, the angle between theeasy axis 249, along which the magnetization of the stripe 222 isdirected, and the current in magnetoresistive sections 257 as shown byarrow 258, is between 0° and 90° and preferably near 45°. Upon exposureof the pole tips 227 and 230 to a magnetic pattern in a disk thatresults in a magnetic flux in the yoke sections 235 and 237 along adirection shown by arrows 262 the magnetic moment of the stripe 222 isrotated in a direction more parallel with current arrows 258 so that themagnetoresistance in sections 257 approaches zero. On the other hand,when the pattern on the disk creates a magnetic flux in the yokesections 235 and 237 in the direction of arrows 264, the magnetic momentwithin MR stripe 222 is rotated to become more nearly perpendicular tocurrent 258 within resistive sections 257, so that magnetoresistance inthose sections 257 rises. This differential resistance based upon thedirection of magnetic flux in yoke sections 235 and 237 creates avoltage difference which is used to read the information from the disk.

A process for constructing the transducer 220 is shown beginning FIG.14. A conventional wafer substrate 300 of silicon, alsimag or otherknown materials is used to form many thousand of the sliders 62 of FIG.4, each containing at least one such transducer 220, after which thesliders are separated from each other and from the wafer. Separation ofthe sliders 62 from the wafer is accomplished by selective etchingeither of the wafer or of a release layer such as copper formed atop thewafer before the sliders are formed. The formation of the sliders 62proceeds in layers generally from a back side of the slider designed toface away from the disk to the disk-facing side of the slider.Initially, electrically conductive interconnects for the coils 240 andMR element 222 are formed of gold, including four spaced apart terminalsthat protrude from the back side and provide mechanical as well asconductive connections to a gimbal and flexure beam structure.

A layer of alumina 303 has been sputtered onto the silicon substrate 300and is then polished and cleaned to provide a planar surface. An MRlayer of Permalloy is then formed in the presence of a magnetic field bysputtering or ion beam deposition to a carefully controlled thickness ofabout 200 Å, the field creating an easy axis of the Permalloy film intoor out of the plane of the paper of FIG. 14. A photoresist is thendistributed atop that film and patterned to protect M stripe 222 whilethe remainder of the Permalloy is removed by ion beam etching (IBE). TheMR stripe 222 is then covered with another photoresist that is patternedto cover slanted portions of the stripe corresponding to barber poleshaped MR sections 257 of FIG. 13. A bias layer 305 of antiferromagneticmaterial such as FeMn is then deposited which pins the easy axis of theMR stripe in a single direction, as shown by arrow 249 of FIG. 13. Aconductive material such as copper is then deposited atop the bias layer305 forming the conductive pattern shown in FIG. 13 including bar 255.The photoresist that had covered areas such as 257 and layer 303 is thenremoved, taking with it any bias layer 305 and conductive layer that hadbeen disposed on top of the photoresist. A protective layer 310 ofalumina is the deposited atop the MR element 222, bar 255 and aluminalayer 303 to a thickness in a range between 125 Å and 1000 Å. Aphotoresist is then distributed atop layer 310 and patterned to protectthat portion of layer 310 covering MR stripe 222 and conductive bar 255,while the remainder of that layer is removed by wet etch or IBE.

Another photoresist layer is then patterned to cover a central portionof the insulation 310 above bar 255 and MR section 257. A NiFe seedlayer 313 is then sputtered to a thickness of about 1000 Å, whereupon asolvent is applied to remove the resist and to lift off any seed layerdisposed on the resist. This photoresist lift-off process avoids theneed for etching or other removal of the thin seed layer that wouldotherwise exist atop the central portion of insulation layer 310, andthus avoids damage to that layer and the MR elements below. Top yokesections 235 and 237 are then formed by window frame plating with gap233 left between those sections disposed above the central portion of MRstripe 222. Yoke sections 235 and 237 overlap MR stripe 222 so as tominimize the interruption of magnetic flux between the yoke sections 235and 237 and the MR stripe 222. One should note that although a single MRstripe is shown, a connected series of such MR stripes may cross backand forth adjacent to the top yoke in order to increase the measurablemagneto-resistance.

FIG. 15 shows a portion of the substrate removed somewhat from andpreferably formed subsequently to the MR stripe 222 and yoke sections235 and 237 in order to illustrate an electrical and mechanicalinterconnection 320 that, after eventual removal of the substrate, willprotrude from the non-disk-facing surface 322 of alumnina layer 303. Thelayer 303 is covered with a patterned photoresist which exposes areas ofthat layer for etching holes 325, the holes being extended into thesubstrate 300 by reactive ion etching (RIE) to form molds for theprotruding terminals 320, which are then seeded with a TiCu layer 327while the yoke sections 235 and 237 and MR stripe 222 are covered with aphotoresist, after which another photoresist is patterned and copper isplated to define leads 330 as well as interconnect terminals 320. Two ofthe leads 330, of which only one is shown, connect with the conductors250 and 252, while another pair of leads provide connection to theelectrical coil 240.

FIG. 16 focuses on one half of generally symmetric transducer 220 inorder to better illustrate its formation. After formation of the yokesections 235 and 237, MR stripe 222 and conductive lead 330, anapproximately 1500 Å thick etch stop layer 307 is then deposited andselectively etched by RIE to remove portions of that layer 307 over theMR stripe 222. A conductive segment 333 is then plated atop an end oflead 330 while the rest of the construction is covered with photoresist.After that, an alumina layer is deposited, which is then lapped andcleaned to form a planar surface upon which coil 240 is formed bythrough plating a spiral pattern of photoresist.

A top view of coil section 240 is shown in FIG. 17. An inner section 335of coil 240 is connected to segment 333, while a similar section 337 isconnected to another segment, not shown, which is connected via a leadsimilar to lead 330 to the exterior of the chip. Coil 240 spiralsoutwardly around yoke section 170 until crossing over at section 339 tospiral about yoke section 172.

Referring again to FIG. 16, another layer of alumina is deposited whichencases and covers coil section 240, the alumina layer then being lappedand cleaned to form a planar surface 342, upon which an etch stop layerof silicon carbide is formed. Atop the SiC etch stop layer 344 a thickerlayer of alumina is deposited, which is then planarized, masked with apatterned resist layer and isotropically etched to form pedestal 175having slanted sides 346. The exposed etch stop layer 344 is thencovered with a photoresist patterned with a hole above an end of yokesection 348, after which an IBE or RIE removes the exposed portion ofetch stop 344. An isotropic etch through the etch stop hole and aphotoresist pattern results in sloping alumina sides 350. The end 348 isthen exposed by RIE or IBE removal of lower etch stop layer 307. Next, abottom yoke 350 is formed by window frame plating on the end 348 ofbottom yoke section 235 and over the terraced insulation that peaks atoppedestal 175, providing a low profile, low reluctance magnetic path thatprojects above the pedestal. After deposit of another thicker aluminalayer 355 atop the structure of FIG. 17, that layer is lapped flat to alevel exposing pedestal 175 and separating bottom yoke sections 170 and172.

FIG. 18 focuses on the process for making the pole tips which adjoin thepedestal and incorporate a high BS layer in the trailing pole tipadjoining the gap, some advantages of which were discussed above.Instead of the solid yoke 350 layer shown in the previous figure,laminated bottom yoke 360 is made of a pair of magnetic layers 362 and365 of permalloy formed by window frame plating with a thinner amagneticlayer 370 of alumina formed by sputtering disposed between the magneticlayers. The yoke 360 curves upward as before due to its formation atopthe amagnetic pedestal 175. The magnetic layers 362 and 365 each have athickness of 1 μm to 3 μm, while the amagnetic layer 370 has a thicknessbetween 100 and 200 nm. Another amagnetic, insulative layer 377,preferably formed of alumina, is deposited atop the yoke layers 362 and365, and then those layers are lapped to form a predetermined separationin the yoke layers atop the pedestal 175, as discussed above with regardto layer 355. A first pole layer 380 is then formed by window frameplating of permalloy on a NiFe seed layer, providing an essentiallyvertical edge 382 to that pole layer. A high magnetic saturationmaterial such as cobalt zirconium niobium or FeAl(N) is then sputteredat an angle 385 to form horizontal layers 388 and a vertical layer 390of high B_(s) material adjoining edge 382.

Referring now to FIG. 19, the horizontal layers 388 have been removed bya vertically directed ion beam etch (113E) leaving the slightlyshortened vertical layer 390 of high B_(s) material. Layer 390, whichhas a precisely controlled longitudinal thickness that may range between100 nm and 400 nm, is to become the portion of the head through whichthe highest flux passes during writing, and so the shape of this layer390 is important in determining the bit shape written on the medium.Vertical layer 395 and horizontal layers 397 of amagnetic material suchas alumina, silicon or silicon dioxide are then formed by angledsputtering in a similar fashion as that described above for the highB_(s) material, after which the horizontal layers 397 are masked andetched to leave the “S” shape shown. A second pole layer 400 issubsequently electroplated, after which lapping is used to remove theportion of that pole layer atop the first pole layer 380 and the upperhorizontal layer 397, leaving the vertical portion 395.

As shown in FIG. 19, the pole layers 380 and 400 are then masked withslightly oversized photoresist pattern 402 of the pole tips 20 and 22,not shown in this figure, after which a rotating IBE is performed at anangle α, removing the photoresist at about the same rate as the exposedpole layers, as shown by dashed lines 404 and 406, to create thehome-plate-shaped pair of pole tips with the vertical portion 395 leftto serve as the gap 27. The angled, rotating IBE leaves the pole tips 20and 22 with vertical outside walls that rise from an angled skirt thatis caused by shadowing during the angled IBE, the skirt providing animproved substrate for the subsequent formation of hard, durablematerial such as diamond like carbon that encases the pole tips and,like the pole tips, slides on the disk.

Referring additionally now to FIG. 21, the photoresist mask 402 has beenformed in the elongated hexagonal shape desired for the pole tips 20 and22 and gap 27, however, the mask 402 is larger than the eventual poletip area, to compensate for removal of a portion of the mask duringetching. The etching is done by IBE with the ion beam directed at apreselected angle α to the surface of the pole layers 380 and 400, whilethe wafer is rotated, in order to form vertical sides of the pole tips20 and 22, aside from a tapered skirt 413, shown in FIG. 22, of the poletips 20 and 22, the skirt 413 acting as an aid to the subsequentformation of the hard wear material 52 that will surround the pole tips.The vertical sides of the pole tips 20 and 22 allows operational wear ofthe pole tips to occur without changing the magnetic read writecharacteristics of the head. On the other hand, the skirt 413 allows thewear material 433 that wraps around the pole tips 20 and 22 to be formedwithout cracks or gaps which can occur, for example, in depositing DLC,preferably by plasma enhanced chemical vapor deposition (PECVD) onto avertically etched pair of pole tips 20 and 22. Although this taperedskirt 413 can be achieved by a variety of techniques, an angled,rotating IBE is preferred to exactingly tailor the vertical pole tips 20and 22 with tapered skirts 413.

The photoresist mask 402 has an etch rate that is similar to that of theNiFe pole layers 380 and 400, so that when the angle α is approximately45° the pole layer 404 and the mask 415 are etched a similar amount, asshown by dashed 404. Pole layer 380, however, is partially shielded fromthe angled IBE by the mask 415, so that a portion 420 of layer 380 thatis adjacent to the mask is not etched, while another portion is etchedas shown by dashed line 406. As the wafer substrate is rotated, notshown, pole layer 400 will have a non-etched portion 425 adjacent to anopposite end of the elongated mask 402, as will areas 427 and 428adjacent sides of the elongated mask. Since areas 427 and 428 areadjacent larger widths of the mask 215 than areas such as 220 and 225and are thus more shielded and etch slower, the rotation of the wafer ispreferably slower during periods when the IBE is angled along theelongated length of the mask (closest either to portion 420 or 425). Theangle α may be changed to further control the shaping of the pole tips20 and 22, for example to employ a greater angle such as about 60°toward the end of the IBE. This rotating, angled IBE is continued for anappropriate time to create a pair of pole tips 20 and 22 having verticalsides with a tapered skirt 413 and a flat, elongated hexagonal topsubstantially centered about the gap 27.

After electrical testing, the wafer carrying the transducer is ready forthe formation of the support pads 68, 78 and 80, as shown in FIG. 22,which focuses on the MAP 68 for clarity. An adhesion layer 430 of Si isdeposited to a thickness of about 500 Å atop the pole tips 44 andalumina layer 377. A layer 433 of DLC is then sputtered onto theadhesion layer 430. An approximately 1500 Å thick layer 435 of NiFe isthen deposited, which is then patterned by IBE with a lithographicallydefined photoresist mask 438 to leave, after IBE, a NiFe mask disposedover the DLC covered pole tips 20 and 22 and over portions of the DLClayer at positions corresponding to the MIPS 78 and 80, not shown inthis figure. The DLC layer 433 covered with the NiFe masks is thenreactive ion etched with O₂ plasma to leave projections of DLC that formthe MAP 68 and MIPS 78 and 80. The MAP 68 and MIPS 78 and 80 are thenlapped to expose the pole tips 20 and 22. The MAP 68 and MIPS 78 and 80are next protected with a photoresist which extends laterally andlongitudinally beyond the edges of each pad, and then an RIE etch usingCF4/O2 removes the Si layer 430 not covered by the resist, leaving aflange of Si which helps to position undercutting of the alumina layer377 further from the MAP and MIPS, resulting in a stronger MAP and MIPSthat are thicker closer to the disk-facing surface. Alternatively, theSi layer 430 can be left over most of the surface to facilitate laserinterferometer testing of chip flatness and tilt. The chip 62 is thenlaser scribed to provide lateral and longitudinal separations from otherchips that have been simultaneously formed on the wafer substrate.

FIG. 23 illustrates an end of a flexure beam 450 that has been formed asa gimbal 460 employed to hold the chip 62 in contact with a rapidlyspinning rigid disk. The beam 450 has four conductive leads 452, 454,456 and 458 that extend along most of the length of the beam and provideelectrical circuits for the coil 240 and the MR element 222, the leadsbeing differentially shaded to facilitate their distinction. The leads452, 454, 456 and 458 are connected with the terminals that protrudefrom the non-disk-facing side of the chip 62 by ultrasonic orthermo-compressive bonding, soldering or other means at areas 462, 464,466 and 468. The convoluted paths between leads 452, 454, 456 and 458and areas 462, 464, 466 and 468 allows the chip 62 to pitch and rollduring sliding on the disk. The beam 450 is laminated, having astiffening layer connected to the conductors 452, 454, 456 and 458 on anopposite side from the chip 62 by an adhesive damping layer.

FIG. 24 shows an information storage system with the beam 450 holdingthe chip 62 in contact with a rigid disk 472 spinning rapidly (1,000 rpmto 8,000 rpm) in a direction of arrow 474. The beam 450 is mounted to anarm 477 of a rotary actuator which pivots about axis 480 to provide thechip 62 access to the magnetic recording surface 484. The recordingmedia of the disk 475 has a large perpendicular anisotropy and lownoise, facilitating perpendicular data storage with the ring head MRtransducer 220.

FIG. 25 focuses on a tremendously magnified cross-section of themagnetic recording surface 484 of the disk 475. A media layer 500 of thedisk 475 may be composed of a number of alternating atomic films ofcobalt (Co) and either paladium (Pd) or platinum (Pt) which are grown ona textured seed layer 505 of Tungsten (W), for example, on a substrate510 of aluminum (Al) or glass, for instance. Whether formed by atomiclayer deposition or as a cobalt based alloy, as shown in this figure,layer 500 grows atop the seed layer 505 in a number of columns 513having a crystallographic C axis substantially perpendicular to thesurface 484. The media layer 500 has a thickness generally in a range ofabout 100 Å to 1000 Å, with a preferable thickness of about 200 Å. Ontop of the media layer 500 a protective overcoat 515 of nitrogenated orhydrogenated carbon, for example, is formed to a thickness of about 100Å.

The seed layer 505 imparts a texture to the disk surface 484 which helpsto reduce friction during sliding. Alternatively, the media layer can becomposed of barrium ferrite (BaFeO), in which case a protective overcoatis not necessary and the head to media spacing is reduced further. Afterwriting with a closely spaced ring head, not shown in this figure,columns 513 are magnetized with fields shown by arrows 318. Groups ofadjoining columns 513 that are magnetized in the same directionrepresent a bit of stored information, such that group 520 represents anup bit, and group 522 represents a down bit. For ultra high densityrecording, individual columns may represent single bits.

1. An information storage system comprising: a core of ferromagneticmaterial, said core having a first pole tip and a second pole tip, saidpole tips being separated by a gap of non-magnetic material; a mediumpositioned adjacent to said pole tips, said medium having a surface; anda conductive coil inductively coupled to said core so that said poletips have opposite polarities when current flows through said conductivecoil, and wherein a magnetic field emanates, from one of said pole tipsand into said medium, with a strength oriented substantiallyperpendicular to said surface that is larger than a maximum strengthoriented parallel to said surface.
 2. The information storage system ofclaim 1, further comprising a layer of magnetic material connected toand positioned between the first pole tip and the gap.
 3. Theinformation storage system of claim 2, wherein the first pole tip has asaturation density and the layer of magnetic material has a saturationdensity, wherein the saturation density of the layer of magneticmaterial is higher than the saturation density of the pole tip.
 4. Theinformation storage system of claim 1, wherein the first pole tip has afirst surface abutting the gap, further wherein the first surface isslanted relative to the surface of the medium.
 5. The informationstorage system of claim 4, wherein the second pole tip has a thirdsurface adjacent to the gap, further wherein the third surface isslanted relative to the surface of the medium.
 6. The informationstorage system of claim 1, further comprising a magnetoresistive sensor7. The information storage system of claim 1, wherein the first pole tiphas a first surface and a third surface and said second pole tip has asecond surface and a fourth surface, wherein each of said first andthird surfaces is connected to the gap.
 8. The information storagesystem of claim 7, further comprising a layer of diamond-like carbonpositioned adjacent to the third and fourth surface.
 9. The informationstorage system of claim 1, wherein one of the first or second pole tipis made of a high magnetic moment material.
 10. The information storagesystem of claim 9, wherein the high magnetic moment material is selectedfrom a group consisting of CoZrNb, FeN, and FeNAl.
 11. A transducercomprising: a core of ferromagnetic material, said core having a firstpole tip and a second pole tip, the pole tips being separated by a gapof non-magnetic material, further wherein said first pole tip has afirst air bearing surface and said second pole tip has a second airbearing surface; and a conductive coil inductively coupled to said coreso that said pole tips have opposite polarities when current flowsthrough said conductive coil, and wherein a magnetic field emanates fromone of said first or second air bearing surface with a strength orientedsubstantially perpendicular to said first or second air bearing surfacethat is larger than a maximum strength oriented parallel to said firstor second air bearing surface.
 12. The transducer of claim 11, furthercomprising a magnetoresistive sensor.
 13. The transducer of claim 11,wherein first and second pole tip are separated from each other by adistance less than one-fifth of a micron and at least 125 angstroms. 14.The transducer of claim 11, wherein a layer of diamond-like carbon ispositioned adjacent to said first pole tip and said second pole tip. 15.The transducer of claim 11, wherein one of the first or second pole tipis made of a high magnetic moment material.
 16. The transducer of claim15, wherein the high magnetic moment material is selected from a groupconsisting of CoZrNb, FeN, and FeNAl.
 17. The transducer of claim 11,further comprising a layer of magnetic material connected to andpositioned between the first pole tip and the gap.
 18. The transducer ofclaim 17, wherein the first pole tip has a saturation density and thelayer of magnetic material has a saturation density, wherein thesaturation density of the layer of magnetic material is higher than thesaturation density of the pole tip.
 19. The transducer of claim 1,wherein the first pole tip has a first surface adjacent the gap, furtherwherein the first surface is slanted.
 20. The transducer of claim 19,wherein the second pole tip has a third surface adjacent the gap,further wherein the first surface is slanted.